Actuators are used in myriad devices and systems. For example, many vehicles including, for example, aircraft, spacecraft, watercraft, and numerous other terrestrial and non-terrestrial vehicles, include one or more actuators to effect the movement of various control surfaces or components. In many applications such as, for example, aircraft flight surface control systems and aircraft thrust reverser actuation systems, the actuators include power drive units, such as motors, that are configured to receive a source of drive power to move an actuator element, and thus the control surfaces or components, to a commanded position. When the control surfaces or components reach the commanded position, the source of drive power may be removed. Thus, many of the actuators that are used include a motor brake, or what is sometimes referred to as a no-back device. The motor brake is configured to prevent motor rotation, and thus hold the actuator in position against the load once the actuator has moved the control surface or component to the commanded position.
The types and configurations of motor brakes that are included in actuators vary. In one particular configuration, the motor brake is configured to prevent motor rotation when it is de-energized, and to allow motor rotation when it is energized. With this configuration, the brake is typically energized during motor rotation, and is de-energized after the motor has driven the actuator to a commanded position and has stopped rotating. Although this configuration is generally safe, reliable, and robust, it may suffer certain drawbacks. For example, if electrical power becomes simultaneously unavailable to the motor and brake during motor operation, the brake will engage and impact the motor with an immediate load. Such an event can degrade or otherwise deleteriously effect the motor and/or the actuator and/or the overall actuation system.
Hence, there is a need for a motor brake system and circuit that addresses one or more of the above-noted drawbacks. Namely, a system and circuit that prevents or at least inhibits the motor brake from engaging, and impacting the motor with an immediate load, if electrical power becomes simultaneously unavailable to the motor and brake during motor operation.